Abstract: A portable speaker device comprising a front mounting plate (1) having two openings (1a, 1b) for sound transmission, two loudspeakers (3a, 3b) each fixedly secured to the front mounting plate for broadcasting through one of the openings, a rear mounting plate extending parallel to the front mounting plate (5), and two enclosure bodies (7a, 7b). These bodies are each formed by a plurality of separate ring-shaped enclosure members (11a1-11a5; 11b1?-11b5) axially movable with regard to each other. The members of each enclosure body have a front member (11a1?; 11b1) secured to the front mounting plate in surrounding relation to one of the loudspeakers and a rear member (11a5; 11b5) secured to the rear mounting plate. In a non-operational position of the speaker device, the mounting plates extend closely to each other, whereby the enclosure bodies have a collapsed shape and the device is very compact.

Abstract: An electromagnetic driving unit includes a magnet part and a coil part that is translatable along a translation axis with respect to the magnet part. A diaphragm extends from the coil part in a substantially radial direction with respect to the translation axis of the coil part. The magnet part includes two permanent magnets and an intermediate magnetic pole element that is sandwiched between the permanent magnets when viewed along the translation axis of the coil part. In order to improve the efficiency of the driving unit, the permanent magnets and the intermediate magnetic pole element are sandwiched between two external magnetic pole elements, and all pole elements have pole faces that are magnetically directed towards the coil part.

Abstract: A loudspeaker includes a frame, a diaphragm and an electric driving arrangement for moving the diaphragm along an axis with respect to the frame. The diaphragm includes an outer conical first diaphragm body and an inner conical second diaphragm body invertedly oriented with respect to and positioned inside the first diaphragm body. The first and second diaphragm bodies each have a base portion and a top portion, the top portion of the first diaphragm body and the base portion of the second diaphragm body being interconnected. The diaphragm is suspended from the frame by a first flexible suspension member extending between the base portion of the first diaphragm body and the frame, and a second flexible suspension member extending between the top portion of the first diaphragm body and the frame. The top portion of the second diaphragm body is attached to a movable part of the driving arrangement.

Abstract: An electro-dynamic loudspeaker includes a chassis (2), a three-dimensional diaphragm (8) and an electromagnetic actuator (6). The diaphragm is connected to the chassis by a first flexible connection (18) provided near a front part (8a) of the diaphragm and by a second flexible connection (20) provided near a back part (8b) of the diaphragm. The actuator includes a stationary actuator element (6a) fixed to the chassis and a translatable actuator element (6b) fixed to the diaphragm. When energized, both actuator elements magnetically co-operate with one another over an air gap (16). In order to realize a flat but powerful speaker, the device as such and the air gap are outside the area (26) enclosed by the diaphragm but within the space (24) between the first and second flexible connections.

Abstract: A passive radiator includes a chassis (11) and a radiator body which is connected to the chassis and which is movable with respect to the chassis along a translation axis (T*). The radiator is capable of displacing comparatively large air volumes. The radiator body includes a central mass element (13a) and at least one mass element (13b) which is arranged concentrically with respect to the central mass element. The radiator further comprises connection units for movably interconnecting each pair of adjacent mass elements and for movably connecting one of the mass elements to an element (11a) of the chassis. Each of the connection units includes two resilient annular connecting rings (5a1, 5a2; 5b1, 5b2), which have two adjacent elements which are parts of said elements secured to them. The connecting rings of at least one of the connection units bound a closed chamber (17a) containing a gaseous medium in order to counteract undesired noises.

Abstract: An electrodynamic loudspeaker comprising a chassis (2), a three-dimensional diaphragm (8) and an electromagnetic actuator (6). The diaphragm is connected to the chassis by a first flexible connecting means (18) provided near a front part (8a) of the diaphragm and by a second flexible connecting means (20) provided near a back part (8b) of the diaphragm. The actuator includes a stationary actuator element (6a) fixed to the chassis and a translatable actuator element (6b) fixed to the diaphragm. When energized, both actuator elements magnetically co-operate with one another over an air gap (16). In order to realize a flat but powerful speaker, the device as such and the air gap are outside the area (26) enclosed by the diaphragm but within the space (24) between both connecting means.

Abstract: A passive radiator comprises a chassis (11) and a radiator body which is connected to the chassis and which is movable with respect to the chassis along a translation axis (T*). The radiator is capable of displacing comparatively large air volumes. The radiator body comprises a central mass element (13a) and at least one mass element (13b) which is arranged concentrically with respect to the central mass element. The radiator further comprises connection units for movably interconnecting each pair of adjacent mass elements and for movably connecting one of the mass elements to an element (11a) of the chassis. Each of said connection units comprises two resilient annular connecting rings (5a1, 5a2; 5b1, 5b2), which have two adjacent elements which are parts of said elements secured to them. The connecting rings of at least one of the connection units bound a closed chamber (17a) containing a gaseous medium in order to counteract undesired noises.

Abstract: Loudspeaker, in particular low-note loudspeaker, provided with a cone-shaped diaphragm having a coil form on which in addition to the voice coil is mounted a piezoelectric transducer in the form of a thin plate capable of pivotal movement. The output voltage of the transducer is degeneratively fed back to the input of an associated amplifier. The plate preferably is rectangular and suspended in rubber mounts along two opposed edges. The mounts form part of a mounting board provided with printed wiring on which an electronic transformation circuit is arranged. A shallow cup in which the mounting board is accommodated ensures that the piezoelectric plate is separated in an airtight manner from the coil form.